1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Generalized type relating mechanism. A type relation R relates a
12 //! pair of values (A, B). A and B are usually types or regions but
13 //! can be other things. Examples of type relations are subtyping,
14 //! type equality, etc.
16 use hir::def_id::DefId;
17 use middle::const_val::ConstVal;
19 use ty::subst::{Kind, UnpackedKind, Substs};
20 use ty::{self, Ty, TyCtxt, TypeFoldable};
21 use ty::error::{ExpectedFound, TypeError};
22 use mir::interpret::{GlobalId, Value, PrimVal};
23 use util::common::ErrorReported;
28 use rustc_data_structures::accumulate_vec::AccumulateVec;
30 pub type RelateResult<'tcx, T> = Result<T, TypeError<'tcx>>;
32 #[derive(Clone, Debug)]
34 ExistentialRegionBound, // relating an existential region bound
37 pub trait TypeRelation<'a, 'gcx: 'a+'tcx, 'tcx: 'a> : Sized {
38 fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx>;
40 /// Returns a static string we can use for printouts.
41 fn tag(&self) -> &'static str;
43 /// Returns true if the value `a` is the "expected" type in the
44 /// relation. Just affects error messages.
45 fn a_is_expected(&self) -> bool;
47 fn with_cause<F,R>(&mut self, _cause: Cause, f: F) -> R
48 where F: FnOnce(&mut Self) -> R
53 /// Generic relation routine suitable for most anything.
54 fn relate<T: Relate<'tcx>>(&mut self, a: &T, b: &T) -> RelateResult<'tcx, T> {
55 Relate::relate(self, a, b)
58 /// Relate the two substitutions for the given item. The default
59 /// is to look up the variance for the item and proceed
61 fn relate_item_substs(&mut self,
63 a_subst: &'tcx Substs<'tcx>,
64 b_subst: &'tcx Substs<'tcx>)
65 -> RelateResult<'tcx, &'tcx Substs<'tcx>>
67 debug!("relate_item_substs(item_def_id={:?}, a_subst={:?}, b_subst={:?})",
72 let opt_variances = self.tcx().variances_of(item_def_id);
73 relate_substs(self, Some(&opt_variances), a_subst, b_subst)
76 /// Switch variance for the purpose of relating `a` and `b`.
77 fn relate_with_variance<T: Relate<'tcx>>(&mut self,
78 variance: ty::Variance,
81 -> RelateResult<'tcx, T>;
83 // Overrideable relations. You shouldn't typically call these
84 // directly, instead call `relate()`, which in turn calls
85 // these. This is both more uniform but also allows us to add
86 // additional hooks for other types in the future if needed
87 // without making older code, which called `relate`, obsolete.
89 fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>)
90 -> RelateResult<'tcx, Ty<'tcx>>;
92 fn regions(&mut self, a: ty::Region<'tcx>, b: ty::Region<'tcx>)
93 -> RelateResult<'tcx, ty::Region<'tcx>>;
95 fn binders<T>(&mut self, a: &ty::Binder<T>, b: &ty::Binder<T>)
96 -> RelateResult<'tcx, ty::Binder<T>>
97 where T: Relate<'tcx>;
100 pub trait Relate<'tcx>: TypeFoldable<'tcx> {
101 fn relate<'a, 'gcx, R>(relation: &mut R, a: &Self, b: &Self)
102 -> RelateResult<'tcx, Self>
103 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a;
106 ///////////////////////////////////////////////////////////////////////////
109 impl<'tcx> Relate<'tcx> for ty::TypeAndMut<'tcx> {
110 fn relate<'a, 'gcx, R>(relation: &mut R,
111 a: &ty::TypeAndMut<'tcx>,
112 b: &ty::TypeAndMut<'tcx>)
113 -> RelateResult<'tcx, ty::TypeAndMut<'tcx>>
114 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
116 debug!("{}.mts({:?}, {:?})",
120 if a.mutbl != b.mutbl {
121 Err(TypeError::Mutability)
124 let variance = match mutbl {
125 ast::Mutability::MutImmutable => ty::Covariant,
126 ast::Mutability::MutMutable => ty::Invariant,
128 let ty = relation.relate_with_variance(variance, &a.ty, &b.ty)?;
129 Ok(ty::TypeAndMut {ty: ty, mutbl: mutbl})
134 pub fn relate_substs<'a, 'gcx, 'tcx, R>(relation: &mut R,
135 variances: Option<&Vec<ty::Variance>>,
136 a_subst: &'tcx Substs<'tcx>,
137 b_subst: &'tcx Substs<'tcx>)
138 -> RelateResult<'tcx, &'tcx Substs<'tcx>>
139 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
141 let tcx = relation.tcx();
143 let params = a_subst.iter().zip(b_subst).enumerate().map(|(i, (a, b))| {
144 let variance = variances.map_or(ty::Invariant, |v| v[i]);
145 relation.relate_with_variance(variance, a, b)
148 Ok(tcx.mk_substs(params)?)
151 impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
152 fn relate<'a, 'gcx, R>(relation: &mut R,
155 -> RelateResult<'tcx, ty::FnSig<'tcx>>
156 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
158 if a.variadic != b.variadic {
159 return Err(TypeError::VariadicMismatch(
160 expected_found(relation, &a.variadic, &b.variadic)));
162 let unsafety = relation.relate(&a.unsafety, &b.unsafety)?;
163 let abi = relation.relate(&a.abi, &b.abi)?;
165 if a.inputs().len() != b.inputs().len() {
166 return Err(TypeError::ArgCount);
169 let inputs_and_output = a.inputs().iter().cloned()
170 .zip(b.inputs().iter().cloned())
172 .chain(iter::once(((a.output(), b.output()), true)))
173 .map(|((a, b), is_output)| {
175 relation.relate(&a, &b)
177 relation.relate_with_variance(ty::Contravariant, &a, &b)
179 }).collect::<Result<AccumulateVec<[_; 8]>, _>>()?;
181 inputs_and_output: relation.tcx().intern_type_list(&inputs_and_output),
182 variadic: a.variadic,
189 impl<'tcx> Relate<'tcx> for ast::Unsafety {
190 fn relate<'a, 'gcx, R>(relation: &mut R,
193 -> RelateResult<'tcx, ast::Unsafety>
194 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
197 Err(TypeError::UnsafetyMismatch(expected_found(relation, a, b)))
204 impl<'tcx> Relate<'tcx> for abi::Abi {
205 fn relate<'a, 'gcx, R>(relation: &mut R,
208 -> RelateResult<'tcx, abi::Abi>
209 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
214 Err(TypeError::AbiMismatch(expected_found(relation, a, b)))
219 impl<'tcx> Relate<'tcx> for ty::ProjectionTy<'tcx> {
220 fn relate<'a, 'gcx, R>(relation: &mut R,
221 a: &ty::ProjectionTy<'tcx>,
222 b: &ty::ProjectionTy<'tcx>)
223 -> RelateResult<'tcx, ty::ProjectionTy<'tcx>>
224 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
226 if a.item_def_id != b.item_def_id {
227 Err(TypeError::ProjectionMismatched(
228 expected_found(relation, &a.item_def_id, &b.item_def_id)))
230 let substs = relation.relate(&a.substs, &b.substs)?;
231 Ok(ty::ProjectionTy {
232 item_def_id: a.item_def_id,
239 impl<'tcx> Relate<'tcx> for ty::ExistentialProjection<'tcx> {
240 fn relate<'a, 'gcx, R>(relation: &mut R,
241 a: &ty::ExistentialProjection<'tcx>,
242 b: &ty::ExistentialProjection<'tcx>)
243 -> RelateResult<'tcx, ty::ExistentialProjection<'tcx>>
244 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
246 if a.item_def_id != b.item_def_id {
247 Err(TypeError::ProjectionMismatched(
248 expected_found(relation, &a.item_def_id, &b.item_def_id)))
250 let ty = relation.relate(&a.ty, &b.ty)?;
251 let substs = relation.relate(&a.substs, &b.substs)?;
252 Ok(ty::ExistentialProjection {
253 item_def_id: a.item_def_id,
261 impl<'tcx> Relate<'tcx> for Vec<ty::PolyExistentialProjection<'tcx>> {
262 fn relate<'a, 'gcx, R>(relation: &mut R,
263 a: &Vec<ty::PolyExistentialProjection<'tcx>>,
264 b: &Vec<ty::PolyExistentialProjection<'tcx>>)
265 -> RelateResult<'tcx, Vec<ty::PolyExistentialProjection<'tcx>>>
266 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
268 // To be compatible, `a` and `b` must be for precisely the
269 // same set of traits and item names. We always require that
270 // projection bounds lists are sorted by trait-def-id and item-name,
271 // so we can just iterate through the lists pairwise, so long as they are the
273 if a.len() != b.len() {
274 Err(TypeError::ProjectionBoundsLength(expected_found(relation, &a.len(), &b.len())))
277 .map(|(a, b)| relation.relate(a, b))
283 impl<'tcx> Relate<'tcx> for ty::TraitRef<'tcx> {
284 fn relate<'a, 'gcx, R>(relation: &mut R,
285 a: &ty::TraitRef<'tcx>,
286 b: &ty::TraitRef<'tcx>)
287 -> RelateResult<'tcx, ty::TraitRef<'tcx>>
288 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
290 // Different traits cannot be related
291 if a.def_id != b.def_id {
292 Err(TypeError::Traits(expected_found(relation, &a.def_id, &b.def_id)))
294 let substs = relate_substs(relation, None, a.substs, b.substs)?;
295 Ok(ty::TraitRef { def_id: a.def_id, substs: substs })
300 impl<'tcx> Relate<'tcx> for ty::ExistentialTraitRef<'tcx> {
301 fn relate<'a, 'gcx, R>(relation: &mut R,
302 a: &ty::ExistentialTraitRef<'tcx>,
303 b: &ty::ExistentialTraitRef<'tcx>)
304 -> RelateResult<'tcx, ty::ExistentialTraitRef<'tcx>>
305 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
307 // Different traits cannot be related
308 if a.def_id != b.def_id {
309 Err(TypeError::Traits(expected_found(relation, &a.def_id, &b.def_id)))
311 let substs = relate_substs(relation, None, a.substs, b.substs)?;
312 Ok(ty::ExistentialTraitRef { def_id: a.def_id, substs: substs })
317 #[derive(Debug, Clone)]
318 struct GeneratorWitness<'tcx>(&'tcx ty::Slice<Ty<'tcx>>);
320 TupleStructTypeFoldableImpl! {
321 impl<'tcx> TypeFoldable<'tcx> for GeneratorWitness<'tcx> {
326 impl<'tcx> Relate<'tcx> for GeneratorWitness<'tcx> {
327 fn relate<'a, 'gcx, R>(relation: &mut R,
328 a: &GeneratorWitness<'tcx>,
329 b: &GeneratorWitness<'tcx>)
330 -> RelateResult<'tcx, GeneratorWitness<'tcx>>
331 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
333 assert!(a.0.len() == b.0.len());
334 let tcx = relation.tcx();
335 let types = tcx.mk_type_list(a.0.iter().zip(b.0).map(|(a, b)| relation.relate(a, b)))?;
336 Ok(GeneratorWitness(types))
340 impl<'tcx> Relate<'tcx> for Ty<'tcx> {
341 fn relate<'a, 'gcx, R>(relation: &mut R,
344 -> RelateResult<'tcx, Ty<'tcx>>
345 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
351 /// The main "type relation" routine. Note that this does not handle
352 /// inference artifacts, so you should filter those out before calling
354 pub fn super_relate_tys<'a, 'gcx, 'tcx, R>(relation: &mut R,
357 -> RelateResult<'tcx, Ty<'tcx>>
358 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
360 let tcx = relation.tcx();
363 debug!("super_tys: a_sty={:?} b_sty={:?}", a_sty, b_sty);
364 match (a_sty, b_sty) {
365 (&ty::TyInfer(_), _) |
366 (_, &ty::TyInfer(_)) =>
368 // The caller should handle these cases!
369 bug!("var types encountered in super_relate_tys")
372 (&ty::TyError, _) | (_, &ty::TyError) =>
381 (&ty::TyUint(_), _) |
382 (&ty::TyFloat(_), _) |
389 (&ty::TyParam(ref a_p), &ty::TyParam(ref b_p))
390 if a_p.idx == b_p.idx =>
395 (&ty::TyAdt(a_def, a_substs), &ty::TyAdt(b_def, b_substs))
398 let substs = relation.relate_item_substs(a_def.did, a_substs, b_substs)?;
399 Ok(tcx.mk_adt(a_def, substs))
402 (&ty::TyForeign(a_id), &ty::TyForeign(b_id))
405 Ok(tcx.mk_foreign(a_id))
408 (&ty::TyDynamic(ref a_obj, ref a_region), &ty::TyDynamic(ref b_obj, ref b_region)) => {
409 let region_bound = relation.with_cause(Cause::ExistentialRegionBound,
411 relation.relate_with_variance(
416 Ok(tcx.mk_dynamic(relation.relate(a_obj, b_obj)?, region_bound))
419 (&ty::TyGenerator(a_id, a_substs, a_interior),
420 &ty::TyGenerator(b_id, b_substs, b_interior))
423 // All TyGenerator types with the same id represent
424 // the (anonymous) type of the same generator expression. So
425 // all of their regions should be equated.
426 let substs = relation.relate(&a_substs, &b_substs)?;
427 let interior = relation.relate(&a_interior, &b_interior)?;
428 Ok(tcx.mk_generator(a_id, substs, interior))
431 (&ty::TyGeneratorWitness(a_types), &ty::TyGeneratorWitness(b_types)) =>
433 // Wrap our types with a temporary GeneratorWitness struct
434 // inside the binder so we can related them
435 let a_types = ty::Binder(GeneratorWitness(*a_types.skip_binder()));
436 let b_types = ty::Binder(GeneratorWitness(*b_types.skip_binder()));
437 // Then remove the GeneratorWitness for the result
438 let types = ty::Binder(relation.relate(&a_types, &b_types)?.skip_binder().0);
439 Ok(tcx.mk_generator_witness(types))
442 (&ty::TyClosure(a_id, a_substs),
443 &ty::TyClosure(b_id, b_substs))
446 // All TyClosure types with the same id represent
447 // the (anonymous) type of the same closure expression. So
448 // all of their regions should be equated.
449 let substs = relation.relate(&a_substs, &b_substs)?;
450 Ok(tcx.mk_closure_from_closure_substs(a_id, substs))
453 (&ty::TyRawPtr(ref a_mt), &ty::TyRawPtr(ref b_mt)) =>
455 let mt = relation.relate(a_mt, b_mt)?;
459 (&ty::TyRef(a_r, ref a_mt), &ty::TyRef(b_r, ref b_mt)) =>
461 let r = relation.relate_with_variance(ty::Contravariant, &a_r, &b_r)?;
462 let mt = relation.relate(a_mt, b_mt)?;
463 Ok(tcx.mk_ref(r, mt))
466 (&ty::TyArray(a_t, sz_a), &ty::TyArray(b_t, sz_b)) =>
468 let t = relation.relate(&a_t, &b_t)?;
469 assert_eq!(sz_a.ty, tcx.types.usize);
470 assert_eq!(sz_b.ty, tcx.types.usize);
471 let to_u64 = |x: &'tcx ty::Const<'tcx>| -> Result<u64, ErrorReported> {
473 ConstVal::Value(Value::ByVal(prim)) => Ok(prim.to_u64().unwrap()),
474 ConstVal::Unevaluated(def_id, substs) => {
475 // FIXME(eddyb) get the right param_env.
476 let param_env = ty::ParamEnv::empty(Reveal::UserFacing);
477 match tcx.lift_to_global(&substs) {
479 let instance = ty::Instance::resolve(
485 if let Some(instance) = instance {
490 match tcx.const_eval(param_env.and(cid)) {
492 val: ConstVal::Value(Value::ByVal(PrimVal::Bytes(b))),
495 assert_eq!(b as u64 as u128, b);
504 tcx.sess.delay_span_bug(tcx.def_span(def_id),
505 "array length could not be evaluated");
508 _ => bug!("arrays should not have {:?} as length", x)
511 match (to_u64(sz_a), to_u64(sz_b)) {
512 (Ok(sz_a_u64), Ok(sz_b_u64)) => {
513 if sz_a_u64 == sz_b_u64 {
514 Ok(tcx.mk_ty(ty::TyArray(t, sz_a)))
516 Err(TypeError::FixedArraySize(
517 expected_found(relation, &sz_a_u64, &sz_b_u64)))
520 // We reported an error or will ICE, so we can return TyError.
521 (Err(ErrorReported), _) | (_, Err(ErrorReported)) => {
527 (&ty::TySlice(a_t), &ty::TySlice(b_t)) =>
529 let t = relation.relate(&a_t, &b_t)?;
533 (&ty::TyTuple(as_, a_defaulted), &ty::TyTuple(bs, b_defaulted)) =>
535 if as_.len() == bs.len() {
536 let defaulted = a_defaulted || b_defaulted;
537 Ok(tcx.mk_tup(as_.iter().zip(bs).map(|(a, b)| relation.relate(a, b)), defaulted)?)
538 } else if !(as_.is_empty() || bs.is_empty()) {
539 Err(TypeError::TupleSize(
540 expected_found(relation, &as_.len(), &bs.len())))
542 Err(TypeError::Sorts(expected_found(relation, &a, &b)))
546 (&ty::TyFnDef(a_def_id, a_substs), &ty::TyFnDef(b_def_id, b_substs))
547 if a_def_id == b_def_id =>
549 let substs = relation.relate_item_substs(a_def_id, a_substs, b_substs)?;
550 Ok(tcx.mk_fn_def(a_def_id, substs))
553 (&ty::TyFnPtr(a_fty), &ty::TyFnPtr(b_fty)) =>
555 let fty = relation.relate(&a_fty, &b_fty)?;
556 Ok(tcx.mk_fn_ptr(fty))
559 (&ty::TyProjection(ref a_data), &ty::TyProjection(ref b_data)) =>
561 let projection_ty = relation.relate(a_data, b_data)?;
562 Ok(tcx.mk_projection(projection_ty.item_def_id, projection_ty.substs))
565 (&ty::TyAnon(a_def_id, a_substs), &ty::TyAnon(b_def_id, b_substs))
566 if a_def_id == b_def_id =>
568 let substs = relate_substs(relation, None, a_substs, b_substs)?;
569 Ok(tcx.mk_anon(a_def_id, substs))
574 Err(TypeError::Sorts(expected_found(relation, &a, &b)))
579 impl<'tcx> Relate<'tcx> for &'tcx ty::Slice<ty::ExistentialPredicate<'tcx>> {
580 fn relate<'a, 'gcx, R>(relation: &mut R,
583 -> RelateResult<'tcx, Self>
584 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a {
586 if a.len() != b.len() {
587 return Err(TypeError::ExistentialMismatch(expected_found(relation, a, b)));
590 let tcx = relation.tcx();
591 let v = a.iter().zip(b.iter()).map(|(ep_a, ep_b)| {
592 use ty::ExistentialPredicate::*;
593 match (*ep_a, *ep_b) {
594 (Trait(ref a), Trait(ref b)) => Ok(Trait(relation.relate(a, b)?)),
595 (Projection(ref a), Projection(ref b)) => Ok(Projection(relation.relate(a, b)?)),
596 (AutoTrait(ref a), AutoTrait(ref b)) if a == b => Ok(AutoTrait(*a)),
597 _ => Err(TypeError::ExistentialMismatch(expected_found(relation, a, b)))
600 Ok(tcx.mk_existential_predicates(v)?)
604 impl<'tcx> Relate<'tcx> for ty::ClosureSubsts<'tcx> {
605 fn relate<'a, 'gcx, R>(relation: &mut R,
606 a: &ty::ClosureSubsts<'tcx>,
607 b: &ty::ClosureSubsts<'tcx>)
608 -> RelateResult<'tcx, ty::ClosureSubsts<'tcx>>
609 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
611 let substs = relate_substs(relation, None, a.substs, b.substs)?;
612 Ok(ty::ClosureSubsts { substs: substs })
616 impl<'tcx> Relate<'tcx> for ty::GeneratorInterior<'tcx> {
617 fn relate<'a, 'gcx, R>(relation: &mut R,
618 a: &ty::GeneratorInterior<'tcx>,
619 b: &ty::GeneratorInterior<'tcx>)
620 -> RelateResult<'tcx, ty::GeneratorInterior<'tcx>>
621 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
623 assert_eq!(a.movable, b.movable);
624 let witness = relation.relate(&a.witness, &b.witness)?;
625 Ok(ty::GeneratorInterior { witness, movable: a.movable })
629 impl<'tcx> Relate<'tcx> for &'tcx Substs<'tcx> {
630 fn relate<'a, 'gcx, R>(relation: &mut R,
631 a: &&'tcx Substs<'tcx>,
632 b: &&'tcx Substs<'tcx>)
633 -> RelateResult<'tcx, &'tcx Substs<'tcx>>
634 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
636 relate_substs(relation, None, a, b)
640 impl<'tcx> Relate<'tcx> for ty::Region<'tcx> {
641 fn relate<'a, 'gcx, R>(relation: &mut R,
642 a: &ty::Region<'tcx>,
643 b: &ty::Region<'tcx>)
644 -> RelateResult<'tcx, ty::Region<'tcx>>
645 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
647 relation.regions(*a, *b)
651 impl<'tcx, T: Relate<'tcx>> Relate<'tcx> for ty::Binder<T> {
652 fn relate<'a, 'gcx, R>(relation: &mut R,
655 -> RelateResult<'tcx, ty::Binder<T>>
656 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
658 relation.binders(a, b)
662 impl<'tcx, T: Relate<'tcx>> Relate<'tcx> for Rc<T> {
663 fn relate<'a, 'gcx, R>(relation: &mut R,
666 -> RelateResult<'tcx, Rc<T>>
667 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
671 Ok(Rc::new(relation.relate(a, b)?))
675 impl<'tcx, T: Relate<'tcx>> Relate<'tcx> for Box<T> {
676 fn relate<'a, 'gcx, R>(relation: &mut R,
679 -> RelateResult<'tcx, Box<T>>
680 where R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a
684 Ok(Box::new(relation.relate(a, b)?))
688 impl<'tcx> Relate<'tcx> for Kind<'tcx> {
689 fn relate<'a, 'gcx, R>(
693 ) -> RelateResult<'tcx, Kind<'tcx>>
695 R: TypeRelation<'a, 'gcx, 'tcx>, 'gcx: 'a+'tcx, 'tcx: 'a,
697 match (a.unpack(), b.unpack()) {
698 (UnpackedKind::Lifetime(a_lt), UnpackedKind::Lifetime(b_lt)) => {
699 Ok(relation.relate(&a_lt, &b_lt)?.into())
701 (UnpackedKind::Type(a_ty), UnpackedKind::Type(b_ty)) => {
702 Ok(relation.relate(&a_ty, &b_ty)?.into())
704 (UnpackedKind::Lifetime(_), _) | (UnpackedKind::Type(_), _) => bug!()
709 ///////////////////////////////////////////////////////////////////////////
712 pub fn expected_found<'a, 'gcx, 'tcx, R, T>(relation: &mut R,
716 where R: TypeRelation<'a, 'gcx, 'tcx>, T: Clone, 'gcx: 'a+'tcx, 'tcx: 'a
718 expected_found_bool(relation.a_is_expected(), a, b)
721 pub fn expected_found_bool<T>(a_is_expected: bool,
730 ExpectedFound {expected: a, found: b}
732 ExpectedFound {expected: b, found: a}